Project Summary Total hip arthroplasty (THA) has been successful in achieving pain reduction, but recent concerns have been raised regarding the development of adverse local tissue reactions (ALTRs). Our previous application focused on utilizing MRI as a noninvasive biomarker of ALTR, so that appropriate intervention can be recommended before extensive damage occurs. By evaluating THAs of different bearing materials we found: 1) MRI can detect and distinguish wear debris from THA; 2) MRI is sensitive to ALTR damage from different articulating surfaces; and 3) variable host-mediated response to wear debris mounts distinct morphologic patterns on MRI. There is continued interest in the evaluation of soft tissues near THAs as traditional THA designs, including metal-on-polyethylene (MOP) and ceramic-on-polyethylene (COP) bearing surfaces, have recently been implicated in ALTRs. It is believed that fretting and corrosion at the head-neck junction is responsible for ALTRs, secondary to flexural rigidity and other implant mechanical features. If a greater prevalence of ALTR is found in components with more flexible connections, this could drive the practice of THA to stiffer connections. In this renewal application, we will evaluate two important causes of implant failure: (1) in designs not traditionally associated with ALTRs such as metal-on-polyethylene (MOP) and ceramic-on-polyethylene (COP) we will assess patients indicated for revision THA surgery with MRI and correlate the imaging metrics to targeted biopsy retrieval obtained at the time of revision (including the trunnion), the extent of tissue damage documented at surgery, and implant retrieval analysis of the neck trunnion, including flexural rigidity analysis; and (2) to longitudinally assess implant integration using qualitative MRI evaluation of the bone-implant interface as well as quantitative MRI techniques, T2 mapping and T2* mapping using MAVRIC-UTE, to evaluate relaxometry at the interface.